Anatomic Range Planning in Positron Emission Tomography

ABSTRACT

Anatomic range planning is provided in positron emission tomography (PET). The user indicates one or more ranges on an image of a patient based on anatomy. Rather than planning by bed position, the planning is based on the anatomy of the patient without reference to the length of the PET detector. The user interface for PET examination avoids overlapping boxes and other confusion based on bed position. Different anatomical ranges may be assigned different PET parameters, such as reconstruction parameters. A processor may automatically alter the examination (e.g., by extending the detection range beyond the region of interest or by increasing duration at an end position) to account for the sensitivity profile since the anatomical region of interest is known. Anatomical region specific directions may be included as part of planning, aiding in performing different protocols for different anatomical ranges.

RELATED APPLICATIONS

The present patent document is a divisional application of U.S. patentapplication Ser. No. 14/182,323, filed Feb. 18, 2014, which claims thebenefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S.Patent Application Ser. No. 61/894,927, filed Oct. 24, 2013, which ishereby incorporated by reference.

BACKGROUND

The present embodiments relate to planning in nuclear medicine, such aspositron emission tomography (PET). In particular, planning is providedfor detecting from a volume of the patient that is longer than the fieldof view of the PET detector.

PET user interfaces support examination planning based on multipleintegral bed positions. In this “stop and shoot” approach, different bedpositions are dictated by the physical axial length of the PET detector.For example, the examination is divided into a plurality of bedpositions spaced less than a length of the PET detector apart. Theexamination region for each bed position corresponds to the length orfield of view of the PET detector. These bed positions are arranged toprovide overlapping examination at different locations.

To define the region to scan of the patient, the user indicates thestarting bed position. The amount of overlap may be defined as well.Since each bed position has a length based on the PET detector, the userdefines the number of bed positions and overlaps to provide forexamining a diagnostic region of interest of the patient. The userconfigures only the number of integral bed positions to define theoverall extent of scan. The user can determine the location of one endof the overall scan range, but the other end location and the positionsof the individual bed positions are determined based on the integralmath of gantry axial field-of-view. The integral math may not match theanatomy of the patient with specific bed positions. The user cannoteasily optimize and adapt the examination protocol to the specific needsof various organ imaging. As a consequence, most users do not attempt tooptimize scanning protocols for the different bed positions.

Another problem with typical PET examinations is sensitivity. Thesensitivity profile of the PET detector across the axial field of viewis triangular or trapezoid shaped, which leads to lower sensitivity andlower signal-to-noise ratio at the end planes of a given bed position.Where multiple bed positions are used, the overall sensitivity profileis generally more consistent within the diagnostic region of interest,but has decreased sensitivity and signal-to-noise ratio at the extremesdue to no overlapping bed positions. Users compensate for the loweredsensitivity and signal-to-noise ratio by manually planning to begin andend the examination in positions that are beyond the area of diagnosticinterest. This further complicates planning for the bed positions andresults in imaging of parts of the patient that are not diagnosticallydesired. Alternatively, the users accept the lowered sensitivity andsignal-to-noise ratio at the end planes.

During operation of the PET detector after planning, the user andpatient are presented with progress references in the form of beds “X”of “Y” and/or time remaining per bed or for the overall scan. The useror system may provide a general instruction to the patient prior to thebeginning of the overall scan, or the user may attempt to manuallyprovide the instruction based on the coarse progress information. Sincegeneral instructions have minimal benefit as not timely and impropertiming may lead to a reduction in examination quality, the usertypically chooses not to give patient instructions during theexamination itself and does not attempt advanced techniques, such asbreath-hold during whole body examinations.

BRIEF SUMMARY

By way of introduction, the preferred embodiments described belowinclude methods, systems, and computer readable storage media foranatomic range planning in positron emission tomography (PET). The userindicates one or more ranges on an image of a patient based on anatomy.Rather than planning by bed position, the planning is based on theanatomy of the patient without reference to the length of the PETdetector. The user interface for PET examination avoids overlappingboxes and other confusion based on bed position. Different anatomicalranges may be assigned different PET parameters, such as reconstructionparameters. A processor may automatically alter the examination (e.g.,by extending the detection range beyond the region of interest or byincreasing duration at an end position) to account for the sensitivityprofile since the anatomical region of interest is known. Anatomicalregion specific instructions may be included as part of planning, aidingin performing different protocols for different anatomical ranges.

In a first aspect, a method is provided for anatomic range planning inpositron emission tomography (PET). An image of a patient as positionedon a bed of a PET scanner is displayed. An indication on the image of ananatomical starting point and an anatomical stopping point of anatomy ofthe patient is received. The anatomical starting point and anatomicalstopping point are different than a length of a detector of the PETscanner or an integral multiplier of the length. The PET scanneroperates as a function of the anatomical starting and stopping points.

In a second aspect, a non-transitory computer readable storage mediumhas stored therein data representing instructions executable by aprogrammed processor for anatomic range planning in positron emissiontomography (PET). The storage medium includes instructions forgenerating an user interface of a PET scanner indicating two or moreranges of patient anatomy, the ranges free of overlap with each otherand at least two of the ranges being of different lengths, each of thelengths being other than a measure of a detector of the PET scanner, andreceiving different PET parameters for at least one of the ranges ascompared to another of the ranges.

In a third aspect, a system is provided for anatomic range planning inpositron emission tomography (PET). An x-ray detector is positioned toreceive x-rays from an x-ray emitter for generating an x-ray image of apatient. A bed positioned between the x-ray emitter and the x-raydetector and in a PET detector. The bed is moveable within the PETdetector. A processor is configured to determine a speed of the bed foran end portion of an entire region of interest of the patient in thex-ray image and/or an extension of bed movement beyond the entire regionof interest of the patient in the x-ray image. The processor isconfigured to determine as a function of sensitivity at the end portion.

The present invention is defined by the following claims, and nothing inthis section should be taken as a limitation on those claims. Furtheraspects and advantages of the invention are discussed below inconjunction with the preferred embodiments and may be later claimedindependently or in combination.

BRIEF DESCRIPTION OF THE DRAWINGS

The components and the figures are not necessarily to scale, emphasisinstead being placed upon illustrating the principles of the invention.Moreover, in the figures, like reference numerals designatecorresponding parts throughout the different views.

FIG. 1 is a block diagram of one embodiment of a system for anatomicrange planning in PET;

FIG. 2 is a flow chart diagram of an example embodiment of a method foranatomic range planning in PET;

FIG. 3 illustrates a user interface for anatomical range planning inPET;

FIGS. 4 and 5 illustrate example approaches to account for thesensitivity of the PET detector in range planning;

FIG. 6 illustrates a user interface for anatomical range planning ofinstructions in PET.

DETAILED DESCRIPTION OF THE DRAWINGS AND PRESENTLY PREFERRED EMBODIMENTS

Examination planning in nuclear medicine examinations is based onanatomy of the patient. Various aspects of the examination may benefitfrom an anatomy centric planning, such as region-by-region scanningconfiguration, region-by-region patient instructions, and automatedentire region sensitivity planning. Any one or more of these aspects maybe used.

In one aspect, a user interface and workflow are provided for anatomicrange planning and variable protocols in nuclear medicine examinations.Using stop and shoot planning, there is no easy way to optimize theacquisition to the individual patient's anatomy. Rather than planning bybed position, a user interface for examination planning is based on anindividual patient's anatomy with different requirements per organ. Theuser may place the scan range at any arbitrary position relative to areference image of the patient's anatomy. Optimizations of the scan maybe configured based on anatomic regions, such as high resolution imagingof the head-and-neck and motion management of the chest within a singlescan of the patient.

In another aspect, a user interface for automatic compensation of noisevariations due to geometric sensitivity in PET imaging is provided. Theuser interface allows the user to define the region of diagnosticinterest based on patient anatomy, and the system automatically accountsfor the lowered sensitivity and signal-to noise ratio in the end planesof this anatomic region. The system adds an additional scanning regionto the ends of the scan range or increases the duration at the endplanes, increasing sensitivity and signal-to-noise ratio in end regionsof diagnostic interest.

In yet another aspect, a user interface and workflow for patientcoaching is based on patient anatomy being scanned. The user interfaceallows automatic patient coaching based upon the anatomical region ofthe patient that is currently or about to-be scanned. For planning, theuser may choose pre-recorded messages to be played audibly or visuallyto the patient prior, during, and/or after the system scans a specificanatomic region of the patient's body. Alternatively or additionally,the user interface may be configured to provide a visual indication tothe user so that manual instructions to the patient may be given withproper timing based on scan progress relative to anatomy. The properlytimed feedback may increase the likelihood of higher qualityexaminations. Properly timed instructions may also enable users toroutinely perform advanced imaging techniques. Advanced imagingtechniques, where the imaging quality is directly dependent upon thepatient following special instructions at the proper time in theexamination (e.g., breath-hold during a portion of a whole bodyexamination), may more likely be successfully performed.

FIG. 1 shows one embodiment of a system 10 for anatomic range planningin nuclear medicine, such as positron emission tomography (PET). Thesystem 10 is part of a PET imaging system, but may be part of a singlephoton emission computed tomography (SPECT) system. The processor 26,memory 28, display 30, and user input 32 are part of a medical imagingsystem, such as the PET system 10. In other embodiments, the system 10is a computer, server, workstation or other processing device thatacquires PET data from a separate scanner and/or that plans for theacquisition of PET data with a separate scanner. The processor 26,memory 28, display 30, and/or user input 32 may be part of an archivaland/or image processing system, such as associated with a medicalrecords database workstation or server. In other embodiments, theprocessor 26, memory 28, display 30, and/or user interface 32 are apersonal computer, such as desktop or laptop, a workstation, a server, anetwork, or combinations thereof. The processor 26 and memory 28 may beprovided without other components for implementing the method.

The system 10 includes a PET detector 12, bed 14, x-ray emitter 16,x-ray detector 18, processor 26, memory 28, display 30, and user input32. Additional, different or fewer components may be provided. Forexample, a network interface is provided. As another example, the x-rayemitter 16 and x-ray detector 18 are separate from the PET detector 12and/or bed 14 or not provided. An optical camera or data created modelor representation of the patient may be used instead of an x-ray image.Other imaging modalities may be used instead of x-ray.

In general, the memory 28 stores previously used, programmed, or otherpre-determined plans and/or data used for generating and operating auser interface for planning. The display 30 displays the user interfaceto the user. The processor 26 controls configuration of the userinterface, operation of the PET detector 12 and the bed 14, and/orreconstruction from data from the PET detector 12.

The system 10, using hardware, software, or hardware and software,interacts with a user for PET planning, controlling operation of the PETscanner, and/or generating a PET image. The system implements the methodof FIG. 2 or another method to provide anatomic range planning in PET.The processor 26 or devices controlled by or connected with theprocessor 26 perform the acts of FIG. 2.

The PET detector 12 is a ring of sensors, forming a tube into which thebed 14 passes or is positioned. A source emits positrons. Any ofdifferent sources of emissions may be provided. For example, thepositrons are emitted from a radioisotope. Any radioisotopes may beused. Different radioisotopes emit or result in photons having differentenergies that will exhibit different characteristics when interactingwith a collimator of the PET detector 12. The radioisotope decays,resulting in either direct photon emission (SPECT) or positroninteraction with electrons and subsequent photon emission (PET). In PET,photons are emitted in generally opposite directions due to the positroninteraction. One or both of these photons are detected by the PETdetector 12, depending on the point of origin, direction of travel, andposition of the PET detector 12. Other sources of photons may be used inother embodiments.

A multi-channel collimator may be provided with the PET detector 12. Thecollimator is an array of apertures. For example, a honeycomb structureof lead septa or plates is provided. Other materials may be used. Eachchannel of the collimator is an aperture or bore through which photonsmay pass. Rather than a hexagon shape, the aperture of the bores mayhave any shape. The septa are thin to minimize blockage of the photons.The multi-channel collimator has a nominally uniform depth or heightthat is the same for each of the bores, but may vary from bore to boredue to manufacturing defects. Any or no multi-channel collimator may beused.

The multi-channel collimator is adjacent to the sensors of the PETdetector 12. The collimator lies adjacent the sensors or between thesensors and the source. A gap may separate the collimator from thesensors. The collimator covers the entire array of sensors or only partof the array. The collimator is placed to cause photons emitted fromsources to pass through one or more bores generally along aperpendicular line to the detector and not pass through at other angles,such as +/−5 degrees from 90 degrees. Photons traveling at asufficiently large enough angle away from orthogonal are blocked fromthe sensors in order to enforce a geometrical relationship on thedetected photons. Due to the bore aperture within the cylinder of thePET detector 12, photons traveling along lines over a range of anglesmay be accepted while photons traveling along ray lines at greaterangles are blocked, defining a field of view of the PET detector 12.

The sensors are operable to detect emissions. The sensors are an arrayof photo multiplier tubes or silicon avalanche photodiodes. Crystalsconnected with the tubes or photodiodes convert the photons into light.The tubes or photodiodes detect the light. The location, energy, and/ortiming of the detection are recorded or processed as a detected photon.

The x-ray emitter 16 and the x-ray detector 18 are connected with ahousing of the PET detector 12. Alternatively, the x-ray emitter 16 andx-ray detector 18 are part of a separate system (e.g., computedtomography, fluoroscopy, or x-ray) sharing the bed 14 with the PETdetector 12 or disconnected from the PET detector 12 and the bed 14.

The x-ray emitter 16 is positioned opposite the x-ray detector 18. Thebed 14 and the patient on the bed 14 are between the x-ray emitter 16and the x-ray detector 18. The emitter 16 and detector 18 may bemoveable or fixed relative to the bed 18. A single scan may scan theentire or majority of the patient, or a sequence of scans are performedto scan the entire or majority of the patient. To scan, the x-rayemitter 16 emits x-rays, which pass through the patient, and thedetector 18 detects the x-rays. The intensity of the detected x-raysindicates the density of the patient along the respective path oftravel.

The detected x-rays are used for an image of the patient. An x-ray imageis generated of the patient. For example, a topogram or projectionthrough the patient from a fixed reference point above the patient iscreated.

The x-ray image shows internal and external anatomy. For example, boneand/or organs (e.g., heart, lungs, skull, brain, back-bone, hip, breast,ribs, and/or intestines) within the patient are represented in theimage. The skin or outer portions of the patient, such as a boundary oredge of the patient from the x-ray viewing perspective, may also berepresented. The arms, legs, head, neck, hips, chest, hands, feet, orother external anatomy may be represented. Filtering, segmentation, orother processes may be used to enhance particular anatomy.

In alternative embodiments, other modalities for representing externaland/or internal portions of the patient may be used. For example, acamera is used to represent external anatomy. As another example,magnetic resonance is used to represent anatomy. The image may show onlyinternal or only external anatomy.

The position of the x-ray emitter 16 and detector 18 relative to the bedand/or the PET detector 12 is known. Calibration, measurement, or fixedrelationship may be used. The x-ray image of the patient indicatesspecific locations that may be used by the PET detector 12. Alignmentbetween the patient and the x-ray detector 18 may be provided usinglaser location.

The bed 14 is a gurney, table, or other patient resting or supportlocation. The bed 14 is robotic, such as providing for mechanical andautomated movement of the patient through the bore of the PET detector12. The bed 14 is positioned or positionable in the PET detector 12 boreand between the x-ray emitter 16 and x-ray detector 18. The bed 14 movesunder control of the processor 26 to different positions for examiningthe patient with the PET detector 12 and/or creating the x-ray image.The tubular or laterally open examination subject bore of the PETdetector 12 encloses a field of view in which the bed 14 and patient arepositioned. The field of view for the x-ray imaging may overlap or beseparate from the field of view for the PET detector 12. The bed 14 mayposition for both PET and x-ray at a same time or sequentially. Thepatient bed 14 may be moved into the examination bore in order togenerate images of the patient.

In one embodiment, the bed 14 operates to move continuously through thebore. PET detection occurs while the bed 14 is moving. The speed of thebed 14 is constant or varies during this continuous bed motionexamination. Alternatively, the bed 14 moves in increments to differentbed positions in a stop and shoot approach. The bed 14 moves, stops, PETdetection is performed, and then the bed moves to the next position torepeat PET detection.

The user input 32 is a keyboard, mouse, trackball, soft buttons, hardbuttons, touch pad, touch screen, combinations thereof, user sensor, orother now known or later developed user input device. For example, theuser input 32 is a combination of devices provided for interacting witha computer or imaging system. The user input 32 is used to receive inputfrom the user for the user interface of the system 10, such as forplanning.

The processor 26 is a general processor, central processing unit,control processor, graphics processor, digital signal processor,three-dimensional rendering processor, image processor, applicationspecific integrated circuit, field programmable gate array, digitalcircuit, analog circuit, combinations thereof, or other now known orlater developed device for generating a user interface, receiving inputfrom a user, displaying an image, controlling the system 10, and/orperforming the acts of FIG. 2. The processor 26 is a single device ormultiple devices operating in serial, parallel, or separately. Theprocessor 26 may be a main processor of a computer, such as a laptop ordesktop computer, or may be a processor for handling some tasks in alarger system, such as being part of the PET scanner housing the PETdetector 12. The processor 26 is configured by instructions, design,hardware, and/or software to perform the acts discussed herein.

The processor 26 is configured to display a user interface. The userinterface includes an image of the patient and locations for entry ofinformation. For example, a box, field, drop down menu, list, or otheruser input option is displayed. The processor 26 also receives inputfrom entry into the user interface. Alternatively or additionally, theprocessor 26 displays information to the user for action by the user.

The processor 26 is configured to perform the method of FIG. 2 oranother method. The processor 26 performs the acts, controls othercomponents (e.g., PET detector 12, bed 14, x-ray emitter 16, and/orx-ray detector 18), receives data from other components (e.g., PET data,bed position data, x-ray image data) to perform the acts, and/oracquires data to perform the acts of FIG. 2. For example, the processor26 manages the user interface, controls PET detection or passes offinformation for control of PET detection, performs PET reconstruction orreceives PET images, and displays PET and/or x-ray images. The processor26 causes the display 30 to output the user interface.

The processor 26 is configured for planning with the user interface. Theanatomy-based planning is provided by the processor 26. Three anatomyrange-based features mentioned below for the processor are discussedfurther with respect to the method of FIG. 2.

The processor 26 allows for definition by the user of different,non-overlapping anatomical ranges and corresponding different PETparameters (e.g., protocols) for the ranges. Alternatively oradditionally, the processor 26 allows for definition by the user andoutput, based on the definition, of instructions for the patientrelative to anatomy.

For stop and shoot, the processor 26 calculates bed positions based onthe user indications of anatomy rather than the user indication bedpositions (e.g., rather than the user indicating the first position ofthe bed, the number of positions, and the amount of overlap).Alternatively, the processor 26 calculates the speed or duration of thebed for different anatomical regions in continuous bed motion detection.

In another alternative or additional embodiment, the processor 26determines a speed of the bed 14 for an end portion of an entire regionof interest of the patient and/or an extension of bed movement beyondthe entire region of interest of the patient based on a user selectedscan range relative to anatomy. The sensitivity profile of the PETdetector 12 is used to account for sensitivity relative the userindication of a diagnostic region of interest of the patient in theimage.

The memory 28 is a graphics processing memory, video random accessmemory, random access memory, system memory, cache memory, hard drive,optical media, magnetic media, flash drive, buffer, database,combinations thereof, or other now known or later developed memorydevice for storing data or video information. The memory 28 is part ofthe imaging system 10, part of a computer associated with the processor26, part of a database, part of another system, a picture archivalmemory, or a standalone device.

The memory 28 stores anatomical range information, planning data, userinterface inputs, user interface configuration, image information,reconstruction instructions, reconstruction data, and/or otherinformation. The memory 28 or other memory is alternatively oradditionally a non-transitory computer readable storage medium storingdata representing instructions executable by the programmed processor 26for anatomic range planning in PET. The instructions for implementingthe processes, methods and/or techniques discussed herein are providedon non-transitory computer-readable storage media or memories, such as acache, buffer, RAM, removable media, hard drive or other computerreadable storage media. Non-transitory computer readable storage mediainclude various types of volatile and nonvolatile storage media. Thefunctions, acts or tasks illustrated in the figures or described hereinare executed in response to one or more sets of instructions stored inor on computer readable storage media. The functions, acts or tasks areindependent of the particular type of instructions set, storage media,processor or processing strategy and may be performed by software,hardware, integrated circuits, firmware, micro code and the like,operating alone, or in combination. Likewise, processing strategies mayinclude multiprocessing, multitasking, parallel processing, and thelike.

In one embodiment, the instructions are stored on a removable mediadevice for reading by local or remote systems. In other embodiments, theinstructions are stored in a remote location for transfer through acomputer network or over telephone lines. In yet other embodiments, theinstructions are stored within a given computer, CPU, GPU, or system.

The display 30 is a monitor, CRT, LCD, plasma, projection, touch screen,printer, or other display for outputting a user interface. The display30 is fed images from a buffer. The images include user interfaceinformation, such as the user interfaces represented in FIGS. 3 and 6.

FIG. 2 shows one embodiment of a method for anatomic range planning inPET or other nuclear medicine imaging. In general, user entry ofanatomical positions of the patient is used for planning and/oroperation of the PET examination. The user interface provides foranatomical-based selections without bed position limitations or withoutuser entry of the number of bed positions, user entry of the overlap ofbed positions, or the display of multiple bed positions. The userinterface allows definition of exclusive or non-overlapping ranges ofanatomical interest and leaves bed positioning and/or speed to theprocessor.

The method of FIG. 2 is performed by the medical system 10 of FIG. 1,the PET scanner, a computer, a processor, or a different system. Forexample, the medical system, an interface of the medical system, and/ora processor of the medical system allows definition of anatomical rangesfor PET examination planning of different protocols by range, determinesthe range of examination to account for sensitivity, and/or determines aspeed of bed motion to account for sensitivity. As another example, thePET scanner provides visual and/or audio instructions appropriate for agiven anatomical range of the patient during the examination or whenmost appropriate.

The acts are performed in the order shown, but other orders may beprovided. For example, act 54 is performed throughout the method, suchas presenting a user interface without the ranges, with the ranges, withPET parameters for the ranges, with patient coaching information for theranges, during operation of the PET scanner, when providinginstructions, and/or when displaying PET images. Similarly, act 50 isperformed as part of generating the user interface, so may be performedwith, before, or after any of the various other acts.

Additional, different, or fewer acts may be provided. For example, actsfor acquiring an image of the patient or other acts for PET examinationare performed. As another example, acts for interacting with the userinterface are provided. In yet another example, acts 56, 58, and/or 62are used in any combination, such as alone, two of the acts, or allthree of the acts (e.g., act 58 and/or 62 are not performed). As anotherexample, act 64 is not performed.

In act 50, an image of a patient as positioned on a bed of a PET scanneris displayed. Alternatively, the image is of the patient at anotherlocation. Once positioned on the bed of the PET scanner, laser markersare used to align the image information with the patient and the patientwith the PET scanner.

The display is on a screen of a workstation, computer, or other deviceused by a specialist, physician, or other for planning a PETexamination. For example, the display of the image of the patient isgenerated as part of a user interface of the PET scanner.

The user interface is generated for planning, confirming a plan,examination of the patient, and/or display of results of PETexamination. The medical system generates the user interface locally orremotely. Using software, hardware or both, the medical system causesdisplay of graphics, images, or other screen outputs for userinteraction. The user interface includes fields, check boxes, selectablebuttons, selectable menus, tabs, or other software generated inputdevices for user interaction. Any navigation structure may be provided,such as including all information on one screen, including a hierarchalstructure where one or more selections lead to other screens withappropriate or narrowed options. Tab structures may be used to configuredifferent aspects or types of information with the user interface (e.g.,tab for patient, tab for physician, and tab for scan).

In one embodiment, the user interface is for configuring the medicalsystem for operation. FIG. 3 shows an example user interface for PETexamination. The configuration may be to scan a patient for imaging. Theuser interface is part of a workflow of the user for operating themedical system and/or for patient diagnosis. The medical system outputs,in the user interface, pre-determined workflow attributes, such asoptions relevant for the medical system and/or the patient. For example,options for scanning a patient are output as part of the user interface.The options are variables. For PET, the options may include a list ofdifferent imaging enhancements, different reconstruction types oroptions, or other PET parameters.

At any point in the process, such as in response to a user trigger, userselection, or automatically, the image of the patient is displayed onthe user interface. The image is of part of the patient or the entirepatient. In the example shown in FIG. 3, the entire patient is shownfrom head to toe. More than one image may be shown, such as images ofdifferent types, with different processing, and/or from different viewangles. The image shows external and/or internal anatomy of the patient.

In one embodiment, the image is an x-ray-based topogram of the patient.The patient as positioned on the bed of the PET scanner is imaged fromabove. The x-ray emitter and x-ray detector connected with or part ofthe PET scanner image the patient. The x-ray image is looking down onthe patient, but may be from any angle. X-ray images provide informationon the density along paths of travel. As a result, the x-ray imagerepresents both external anatomy (e.g., head, legs, chest, arms, neck,and abdomen) and internal anatomy. In the example of FIG. 3, the lungsand heart are represented in the graphic used to represent an actualx-ray image. In alternative embodiments, the image is an optical image,such as from a camera, an ultrasound image, a magnetic resonance image,or a PET image taken as a precursor to further examination.

In act 52, an indication of an anatomical starting point and ananatomical stopping point is received. The user uses the user input toindicate the range, line, point, or other anatomical locations. Forexample, the user drag and drops, clicks and drags, selects, slides,rotates, or otherwise interacts with a graphic (e.g., box, line, orother shape) on the image. The user may position boxes with or withoutoverlap. The length or axial extent of each box may be changed or set bythe user based on the anatomy of the patient. The user may place a lineto define different ranges. As another example, the user is prompted toclick or select one or more locations where a line is to be placed.

In alternative embodiments, a processor identifies specific anatomy andselects or indicates the anatomical locations. The processor selectedlocations may be displayed for user confirmation.

The indication is relative to anatomy of the patient. The image of thepatient is of anatomy. Specific anatomy may be selected, such asindicating a range or axial extent of an organ or group of organs. Forexample, the anatomy is divided into head and neck, chest, abdomen, andleg ranges as represented in FIG. 3. Other anatomical specificindications may be used, such as selecting a range covering an organ(e.g., lungs). Depending on the reason for the PET examination, alocation may be of increased interest. For example, a narrow chestregion corresponding to a patient's breasts may be of particularinterest for a whole-body examination performed due to a diagnosis ofbreast cancer. The breast region is indicated as one anatomical range.While shown as axial or length ranges, the range may be defined alongone or more other dimensions.

The anatomical starting and stopping points define a range. For example,the user places boxes for four ranges 36 shown in FIG. 3. Additional,different, or fewer ranges may be provided. The user may place separatorlines (e.g., dashed lines) or boxes to separate anatomical ranges or theentire region 34 of diagnostic interest into separate ranges 36. Theseparate ranges 36 do not overlap. A starting point may be the stoppingpoint of a previously identified range. There is no parameter used toset the amount of overlap. The separate ranges 36 are defined relativeto anatomy and are not necessarily based on the length of the PETdetector or an integral multiplier of that length. The indications aredisconnected from the PET detector dimensions or detectioncharacteristics. The indications are arbitrary or may be anywhere alongthe patient rather than at fixed increments relative to the PETdetector.

The starting and stopping points may be for any portion of the entireregion 34 of interest. Each separate range 36 has a starting andstopping point. The entire region 34 of interest likewise has anatomicalstarting and stopping points. The user may position a box, positionlines, or select points to define the entire region 34 of interest. Asshown in the example of FIG. 3, the entire region 34 is for a whole bodyscan. Parts of the body may not be scanned even in a whole body scan,such as the feet and top of the head. In other embodiments, the entireregion 34 is smaller, such as being just the chest and abdomen ranges36, just the abdomen range 36, just the chest range 36, or other portionof the patient. Alternatively, the entire patient is the entire region34.

Any order of indication may be used. For example, the entire region 34is defined by sequentially indicating different ranges 36. As anotherexample, the entire region 34 is indicated, and then portions of theentire region 34 are indicated to provide the separate ranges 36. Ineither approach, anatomic regions 36 of the patient may be definedwithin the overall scan range (e.g., entire region 34) to allow fordifferent values for variables by anatomy in protocol optimization.

The indications are for anatomic regions correlated with patientanatomy. The indications are arbitrary relative to the PET detector orrelative to bed positions, other than any physical limitations of thetotal range of bed motion. Depending on bed operation, any level ofresolution in anatomical marking may be used, such as 2 mm. Theanatomical starting point and anatomical stopping point for any rangemay be different than a length of a detector of the PET scanner or anintegral multiplier of the length. A given anatomical range 34, 36 maybe longer or shorter than the PET detector or an examination length ofthe PET detector at a given position. The anatomical starting andstopping points are provided without an indication of bed position, asanatomy is the determining factor rather than bed positions. User orprocessor input is of positions arbitrary relative to the PET scanner asthe anatomical starting and stopping points are relative to the image ofthe patient and without PET field of view limitations.

In one embodiment, the user selects from a list of anatomical ranges orthe processor provides initial separation. The user then indicates thelocations each of the pre-determined anatomical ranges. In otherembodiments, the user indicates a range and then labels the range usingany terminology or using names from a menu. Any amount of processorassistance and/or pre-determined or standardized ranges and/or rangenames may be used, including none.

In act 54, a user interface showing the ranges is generated. The userinterface is generated as part of providing the indications, aftercompletion of setting the indications, or at other times. The userinterface is displayed for interaction with the user. As the userinteracts with the user interface as part of a workflow for diagnosis,planning, and/or imaging, the user interface is updated. The userinterface is generated or updated in response to user input of one ormore of the anatomical ranges 34, 36 on the image of the patient. Eachupdate may include all, some, or none of the previously receivedindications of the anatomical ranges.

The generated user interface includes the image of the patient withoverlaid or adjacent indication of the ranges of the patient anatomy.For example, FIG. 3 shows color coded bars. Color coding may instead oradditionally be provided as an overlay on the image. Brackets may beused to show the anatomical ranges 34, 36. Arrows may be used to showthe ranges or separation of ranges 34, 36. Boxes (e.g., solid box forentire region 34), lines (e.g., dashed lines separating the entireregion 34 into separate anatomical ranges 36), or pattern overlay mayindicate the different ranges 34, 36. Any combination of these or otherindications of separate portions or the entire region 34 may be used.

The ranges 36 indicated in the user interface are free of overlap witheach other. Different ranges 36 have the same or different lengths. Forexample, FIG. 3 shows each of four anatomical ranges 36 having differentlengths from all other of the anatomical ranges 36. The user interfacedisplayed to the user is free of bed position indicators. The lengths ofthe ranges 36 are not a measure of the detector of the PET scanner, butare instead indications of anatomy.

In act 56, PET parameters are received for the examination of differentportions of the patient. PET parameters are any setting for the PETexamination. For example, different PET reconstruction parameters arereceived. Reconstruction parameters may include the protocol or methodused for reconstruction, such as back projection, 3D iteration, pointspread reconstruction, motion management reconstruction, high definitionreconstruction, low definition reconstruction, or others. Thereconstruction parameters may be values for variables used inreconstruction. The PET parameters may be for enhancements, such as atype of filter, filter setting, resolution, or motion compensation(e.g., breathing indicator or ECG synchronization). Any variable used inPET examination may be a PET parameter.

The parameters are received from user entry or processor selection. Forexample, FIG. 3 shows a portion 40 of the user interface for enteringPET parameters. The user selects an anatomical range on the image, colorbar, or in the range labels 38. Color coding may be used to relate theranges 36 from the image to the ranges in the portion 40. The anatomicregions are color coded for easy reference when defining scan andreconstruction parameters elsewhere in the user interface. Symbols,patterns, sequence, or other relational approaches may be used.Relational information is not used in other embodiments.

Different PET parameters are provided for the different ranges 36. Theuser selects, inputs, or otherwise enters one or more PET parameters foreach of the different ranges. For example, an ultra-high definitionreconstruction is selected from a list in portion 40 for the selectedhead and neck region in portion 38. For the legs anatomical region, afaster, simpler, or lower resolution method for reconstruction may beselected. For the chest region, a motion compensated (e.g., motionmanagement) enhancement or method may be selected. The processordetermines values for variables based on the selected PET parameter.

Different PET parameters or values of the parameters are selected forthe different regions. The PET examination may be optimized for speed,resolution, or other reason by anatomic region. One anatomic region maybe emphasized over others or different approaches may be used to accountfor the differences in anatomy. For example, the legs may not require asmuch image detail for a given PET examination, so a reconstructionmethod associated with greater speed is used as compared to otherregions. As another example, the PET examination for the chest isperformed more rapidly (e.g., faster bed movement in the region incontinuous bed motion scanning) to avoid a user with breathing problemshaving to hold their breath. Alternatively, motion management (e.g.,breather or ECG trigger) and a slower PET examination time are providedfor the chest region for the same reason. One or more anatomical regionsmay share some or all of the selected PET parameters. The selection isbased on the reason for the PET examination and the anatomy, so may varyby patient, physician, application, region, time, or location.

Using the user interface, anatomic regions may be configured fordifferent scan optimizations or enhancements based on the needs of thepatient's anatomy located in each region. For example, reconstruction isdefined based on the anatomic range. Reconstruction optimizations aredetermined by the unique needs of the different anatomic ranges 36. Asanother example, operations or processes in addition to thereconstruction method are selected or not as enhancements. Theseenhancements are determined by the unique needs of the differentanatomic ranges 36.

For continuous bed motion, the user may input a different bed speed fordifferent regions. This may result in more duration of the bed in agiven anatomical region as compared to others. Alternatively, theselection of the reconstruction method and/or an enhancement results indifferent bed speeds for different regions. In other embodiments, theuser does not indicate any bed speed, but the processor determines thebed speed based on the selected PET parameters.

Another portion of the user interface shows values determined by theprocessor in response to selections by the user in portions 38, 40, andof the ranges 34, 36. The table 42 shows speed, duration, and distancefor each of the regions. In other embodiments, the user may enter valuesin the table 42, which are then reflected in the ranges 36 or parameterentry portions 38, 40. In alternative embodiments, the table 42, theenhancement selection, the reconstruction method, and/or color bar arenot provided. Additional or different selection items or user interfacecomponents may be provided.

In act 58, the entire anatomical range 34 (e.g., starting and stoppingpoints) is used to account for sensitivity of the PET detector. The PETdetector has a sensitivity profile for a given position. The profile maybe measured, assumed, or determined using calibration or type of PETdetector. Over the entire range 34, the sensitivity profile may also oralternatively be determined. For the step and shoot approach, thesensitivity profile is based on the bed positions and the duration ateach bed position. For continuous bed motion, the sensitivity profile isbased on the speed or duration as the bed moves relative to the PETdetector. In either approach, the sensitivity at the ends of the entireregion 34 is lower than elsewhere, dropping off rapidly. Signal-to-noiseratio also drops at the ends of the range.

FIGS. 4 and 5 graphically represent the locations of reducedsensitivity. The entire region 78 is the anatomic locations for whichdiagnostic information is sought. Within that entire region 78, areas 80are imaged areas or volumes with increased noise due to reducedsensitivity relative to the remainder of the imaging area or region 78.Without accounting for this sensitivity and signal-to-noise drop off,any PET images of the entire region 34 of diagnostic interest may havepoor quality for locations within about ½ a detector length of the ends.

To account for the sensitivity drop off, the anatomical region 34 ofinterest is used. By indicating the region of interest based on anatomy,the locations for which good or sufficient quality imaging is sought areknown. The processor may then adjust the actual examination to accountfor the decrease in sensitivity at one or both ends of the examinationrange. FIG. 4 represents one approach, adding to the extent or range ofexamination. FIG. 5 represents a different approach, increasing theduration of the examination near the ends. Only one of the twoapproaches is used for a given end, or both approaches may be used incombination for a given end. The sensitivity is increased by duration orextension at one or both ends of the entire anatomical region 34 ofinterest.

The processor receives the anatomical region 34 from the user interface.Using the sensitivity profile, the processor calculates the extensionand/or duration to be used. The sensitivity profile is used to determinethe magnitude of the extension and/or duration. For a given PETdetector, the magnitude may be pre-determined, so is the same for anygiven examination. Different magnitudes for different situations may beprovided, such as magnitude depending on the overall length of theanatomical region 34, the speed of bed motion due to the method selectedfor a given anatomical range 36 at the end, or other factor. From theuser perspective, the anatomical region 78 is provided, and theprocessor handles the sensitivity part rather than requiring the user toposition beds while considering sensitivity as well as anatomy.

FIG. 4 shows computed extensions 82. The anatomical range is expanded bythe processor so that the locations of lower sensitivity and highernoise are moved entirely or partly out of the anatomical region 78 ofinterest for diagnosis. The additional region is used for examining thepatient (e.g., detecting emissions). However, the additional region(i.e., extensions 82) may not be used for imaging. Instead, the additionresults in more emission data being collected in the areas 80 of theanatomical region 78 of interest. The system automatically adjusts thebeginning and end positions of the scan to optimize the sensitivityprofile across the desired imaging area or region 78. The additionalincluded scan area or extensions 82 may ensure image quality acrossentire desired imaging area or region 78.

FIG. 5 shows a computed increase in duration. The PET detector ismaintained at or proceeds more slowly in an end region 84 of theanatomical region 78 of interest. The end region 84 corresponds to onelength of the PET detector. The system adjusts the scan duration of thearea equal to the axial length of the scanner field-of-view at thebeginning and end of the desired imaging area or region 78. Inalternative embodiments for continuous bed motion examination, the endregion 84 may be greater or lesser length than the PET detector field ofview. Within the end region 84, the bed moves more slowly and/or detectsfor a longer time than would otherwise occur given the examinationsettings. For example, the bed may be configured to move at one speedthroughout an anatomical range that includes the end region. Due to thesensitivity, the bed moves at the configured speed for part of theanatomical range and moves more slowly at another part (i.e., the endregion 84). Additional time is included in the scan area or region 78 toensure image quality across the entire desired imaging area.

In act 60 of FIG. 2, the PET scanner operates as a function of theanatomical starting and stopping points. The user initiates the scan,such as activating in the user interface. The processor then controlsthe bed and/or PET scanner to examine the patient and/or generate a PETimage.

The anatomical ranges are used for controlling operation of the PETscanner. Any operation of the PET scanner may be controlled using theanatomical information. For example, the speed and resulting duration(continuous bed motion) or just duration (step and shoot) within a givenanatomical range is determined based on the selected PET parameters forthe anatomical range. The duration and/or speed are different or thesame for different anatomical ranges. The reconstruction for thedifferent anatomical ranges is different or the same, depending on thesettings (e.g., method and enhancements) selected for the anatomicalranges. Different reconstruction parameters are used for data fromdifferent anatomical ranges. Other PET scanning may be different due tothe different settings.

The bed is controlled to provide the desired speed or duration. Forcontinuous bed motion, the center or other location of the PET detectorrelative to the ends of the anatomical ranges is used to change from onespeed to another. For step and shoot, the processor sets bed positionsby anatomical range, avoiding overlap between ranges. During operation,the bed is positioned and stays at the assigned position for a givenduration, providing equal distribution through each given anatomicalrange. A given bed position may be used in more than one range, such asan overlapping bed position set by the processor to avoid sensitivityreduction.

In one embodiment of operation of the PET scanner, the entire range ofthe PET scanning is extended. For example, an extra bed position or anextended region of continuous bed motion is added onto the region ofinterest. The bed is operated to provide for the extension in scanning.Emissions are detected over a greater extent of the patient than desireddiagnostically. For continuous bed motion, emissions are detected whilecontinuously moving the bed in extended areas. The entire movement rangeof the bed motion is based on the anatomical starting and stoppingpoints plus the added extension for sensitivity. The system begins thescan by starting the field-of-view beyond the desired imaging area,and/or the system ends the scan by stopping the field-of-view beyond thedesired imaging area.

In another embodiment, the bed is moved at different speeds in therespective anatomical ranges based on the sensitivity of the PETdetector. At the ends of the entire region of interest, the bed isslowed or duration is increased. The system begins the scan by startingthe field-of-view at the beginning edge of the desired imaging area,and/or the system ends the scan by stopping the field-of-view at theending edge of the desired imaging area. At those beginning and endinglocations as well as adjacent locations, the duration is increased toaccount of sensitivity.

In act 62, patient instructions are provided based on the anatomicalrange. As the PET scanner operates, the bed is positioned relative tothe PET detector for sensing from a field of view. The field of view ofthe PET detector changes. When the field of view is at, nearing, orleaving a particular anatomical range, instructions may be provided tothe user and/or the patient. For example, when the center, a leadingedge, or other part of the field of view contacts or begins to cover anend of an anatomical range 36, instructions are provided. In the exampleof FIG. 6, the field of view 92 is shown leaving a head region andbeginning to acquire data for a chest region. Other trigger points maybe used, such as when the field of view is within a predetermined or setdistance of the anatomical range.

The instructions are anatomic region specific. Different instructionsmay be provided for different anatomical regions 36. One or more regionsmay not include instructions. When the first region to be examined isassociated with instructions, the instructions are given before PETscanning and/or as the PET scanning starts. The instructions may berepeated or not repeated during the scan of that anatomical region. Forsubsequent anatomical regions, including intermediate and the lastregions, the instructions are given after the PET scan or examinationstarts and before completion. The instructions may be given during,before, or after the scan of a given anatomical region. Someinstructions occur after the start and before the end of PET scanning ofa given protocol or workflow.

The instructions are for specific anatomical ranges. For example, thechest region may be examined. During examination of the chest region,the patient is instructed to hold their breath. Rather than instructingthe patient to hold their breath at the beginning of a whole bodyexamination, the instructions are provided at the relevant time, makingit easier on the patient. Other instructions than breath hold may beprovided. For example, the user is instructed where to position theirarms. During scanning of an abdominal region, the arms may be positionedabove the patient's head. During scanning of the legs, chest, and headregion, the arms are positioned at the patient's side. Any anatomicregion specific instructions may be provided. Other audio may vary byregion, such as music being played or comforting statements or images.

The instructions are audio or video instructions. For example, a speakerof the PET scanner provides audio instructions. The audio instructionsare a clause, command, or sentence. Alternatively or additionally, abeep or other sound or tone is made to indicate when to do something. Asanother example, the user interface or a display oriented for viewing bythe patient displays text, symbols, animation, or other instructionsindicating what the patient is to do. Both audio and video instructionsmay be provided.

The instruction is for the user, the patient, or the user and thepatient. For example, the instruction indicates what the patient is todo. The instruction may be communicated to the patient, or theinstruction may be communicated to the user for the user to pass on tothe patient. FIG. 6 shows an example in the portion 94 of the userinterface. The video instructions (e.g., “Breath in, breath out, stopbreathing”) are to the user on the user interface. Timing information isalso given so that the user delivers the instructions at the desiredtime relative to the anatomy being scanned. In a further example, thePET scanner may play a recording with the same instructions. The userinterface is used to show the user what instructions to expect. Inalternative embodiments, the instructions are for the user to dosomething rather than the patient. For example, the user is instructedto move part of the patient, deliver a drug, or to shield themselveswhen an x-ray image is acquired during the PET examination.

The user may use the user interface to configure the PET scanner forproviding the instructions. For example, selecting a reconstructionmethod for the chest region that does not include motion management(e.g., breathing belt triggering) may trigger automatic configuration toprovide breath hold instructions. As another example, inputs forpossible instructions are provided for user entry (e.g., menu or dropdown list) during configuration of the examination.

FIG. 6 shows input or selection of instructions in portion 90. No, oneor more different instructions may be selected for each anatomicalregion. In the example of FIG. 6, three different instructionsassociated with different times during the scan of the chest region areprovided. The messages may be targeted to specific times within the scanof the appropriate anatomic region.

The configuration occurs as part of any workflow. For example, the userselects a region to configure the instructions. As another example, theuser is working on configuring for a given anatomical region and isprovided with instruction configuration options. The portion 90 of theuser interface is provided with appropriate fields or options forselecting instructions. The user selects the instructions or entersinstructions. For example, the user selects from a drop down listpopulated with pre-determined instructions appropriate for a givenanatomical region and/or PET parameters for that region. As anotherexample, the user types in words to be read or the instructions to begiven. The patient's name may be included so the instructions are moreacceptable or polite.

An option for enabling or disabling instructions may be provided. Forexample, the user selects instructions or not for a given selectedanatomical region using the buttons 96. The selection is made for eachregion. A default of no instructions or some generic instructions may beprovided.

During operation of the PET scanner, the instructions are provided basedon the configuration in the planning. The region being scanned or thefield of view relative to the patient may be indicated on the userinterface during operation (e.g., show the field of view 92 moving alongor relative to the patient). Instructions corresponding to that regionor the next anatomical region may be displayed or communicated to theuser or patient. The instructions may include information as to when theinstructions are to be carried out, such as telling the patient to holdtheir breath in five seconds or telling the patient to keep holding forten more seconds during a breath hold.

In act 64, PET images are displayed. Using the reconstruction orreconstructions, the detected emissions for a volume are provided. Aplanar or volume (e.g., three-dimensional imaging) image may begenerated from the detected emissions. Separate PET images for theseparate regions may be provided. One PET image from data of differentanatomical regions may be generated. Different portions of the image maybe responsive to different amounts of PET data, differentreconstruction, different bed speeds, or other differences. Any PETimaging may be used.

The PET image is of part or the entire region 34 of interest. Data fromlocations outside the anatomical region 34 of interest is not used forimaging. For example, data from the extensions 82 of FIG. 4 is not used.The extension provides for the field of view to dwell on the end portionof the region 34 of interest longer, providing greater sensitivity forthat portion. The region 34 of interest is an anatomical region that thephysician wants scanned. The extension is a mechanism for better qualityimaging of the region 34 of interest, so is not part of the region 34 ofinterest that is imaged. In alternative embodiments, data from outsidethe region 34 of interest is included in the image.

While the invention has been described above by reference to variousembodiments, it should be understood that many changes and modificationscan be made without departing from the scope of the invention. It istherefore intended that the foregoing detailed description be regardedas illustrative rather than limiting, and that it be understood that itis the following claims, including all equivalents, that are intended todefine the spirit and scope of this invention.

I (We) claim:
 1. A system for anatomic range planning in positronemission tomography (PET), the system comprising: a PET detector; anx-ray emitter; an x-ray detector positioned to receive x-rays from thex-ray emitter for generating an x-ray image of a patient; a bedpositioned between the x-ray emitter and the x-ray detector and in thePET detector, the bed moveable within the PET detector; and a processorconfigured to determine a speed of the bed for an end portion of anentire region of interest of the patient in the x-ray image and/or (2)an extension of bed movement beyond the entire region of interest of thepatient in the x-ray image, the processor configured to determine thespeed and/or the extension as a function of a sensitivity profile of thePET detector at the end portion of the entire region of interest.
 2. Thesystem of claim 1, further comprising a display for displaying the x-rayimage of the patient.
 3. The system of claim 1, wherein the x-ray imageis an x-ray based topogram of the patient, the topogram including theanatomy comprising an internal anatomical structure of the patient. 4.The system of claim 1, wherein the processor selects a first startingpoint and a first stopping point which define a first range.
 5. Thesystem of claim 4, wherein the processor selects a second starting pointand a second stopping point which define a second range.
 6. The systemof claim 5, wherein the processor selects the first range and the secondrange without a requirement of PET detector dimensions or PET detectorcharacteristics.
 7. The system of claim 5, wherein the first range andthe second range do not overlap.
 8. The system of claim 5, wherein theprocessor assigns a first parameter to the first range and a secondparameter to the second range.
 9. The system of claim 8, wherein thefirst parameter is different than the second parameter.
 10. The systemof claim 8, wherein the first parameter is the same as the secondparameter.
 11. The system of claim 8, wherein the processor adjusts aspeed of the bed based on a value or feature of the first parameter. 12.The system of claim 8, wherein the processor adjusts a resolution of thePET detector based on a value or feature of the first parameter.
 13. Thesystem of claim 8, wherein the processor adjusts a speed of the bedbased on a value or feature of the second parameter.
 14. The system ofclaim 8, wherein the processor adjusts a resolution of the PET detectorbased on a value or feature of the second parameter
 15. The system ofclaim 5, wherein selection of the first range and the second range isbased on an anatomy of the patient and not on a bed position.
 16. Thesystem of claim 1, wherein the processor provides continuous bed motion.17. The system of claim 1, wherein the processor provides stop and shootbed motion.
 18. The system of claim 16, wherein the sensitivity profileis based on a speed or duration as the bed moves relative to the PETdetector.
 19. The system of claim 17, wherein the sensitivity profile isbased on a bed position and a duration at each bed position.
 20. Thesystem of claim 5, wherein a signal to noise ratio is reduced at an endof the first range and at an end of the second range.